Have you ever seen a guy with biceps that look impressive from the side, but then all the size vanishes when they're viewed from the front? Conversely, have you seen biceps that appear thick and meaty from the front, but viewed from the side, they're flat and shapeless? Apparently one of the biceps heads has developed while its brother has lagged behind.

I'm talking here about the good ol' biceps brachii. The other muscles that make up the elbow flexors aren't the focus for now. The biceps brachii has two heads running parallel to one another along your upper arm. The short head runs on the inside of the arm, closest to the chest, and adds to the thickness when viewed from the front. The long head runs along the outside of the arm and forms the peak when flexed. If you're genetically lucky, you may have been gifted with an obvious split between the two heads.

If not, how can a weightlifter target one of the heads over the other? My intention was to answer that question in this article, but truthfully, the deeper I dove into the research, the more conflicting information I discovered. Some trainers advocate a supinated (bent) wrist, others don't. Others say it's all about the width of your grip, while some prioritize the position of the elbows in relation to the torso.

I'm not convinced that any of these theories are true for everyone. Most likely, the shape of your biceps is largely genetic, so if you have one head that stubbornly refuses to grow like its big brother, blame your parents. Rather than giving out advice I don't buy myself, I challenge you to experiment with my favorite techniques to see what works for you.

In the end, whether it's possible to hit one biceps head over the other, doesn't it make sense to attack your biceps from all different angles anyway? Here are some classic biceps-head-isolation movements that should be enough to get you two tickets to the gun show—one for each head, right?

The Long-Head Isolator 1: Alternating Incline Dumbbell Curl

My personal favorite exercise, one reputed to work the long head heavily, is the alternating incline dumbbell curl. Here's how I perform it with a little added intensity:

Set an incline bench at about 30 degrees. Grab two dumbbells on the lighter side of what you'd normally curl. Lie back on the bench and let the bells hang straight down so as to fully stretch out your biceps. Sometimes, I choose to start the curl in a hammer position (palms facing in) and then supinate the hand as I curl one of the weights. For that move, I hold the bell with my thumb against the inside plate so it's more difficult to supinate the hand.

Sometimes I'll start with my hands in a fully-supinated position. If that's my choice, I like to hold the bell with my little finger pressed against the inside plate to add more weight to my thumb side of the bell. This way, I feel a much deeper stretch at the bottom of the curl. I hold this fully supinated position all way up to full contraction.

The most common mistake most lifters make with this exercise is to allow their elbow to move forward as they curl the weight up. I like to take these reps to failure and then sit up on the bench for a couple more reps before finally standing up and squeezing out a couple more while maintaining form.

Long-Head Isolator 2: Standing Barbell Curl

The standing barbell curl can emphasize the long head as long as you use a narrow grip and don't allow your elbows to come forward from your body. Your biceps should be fully contracted in the top position. Keep your chest out and your shoulders back. If you lean your torso slightly forward as the weight comes up, it will help maintain the stress on your biceps.

The first two mistakes remove all the tension from your biceps. I often see the third mistake taking the form of lifters who do curls with their arms locked at 90 degrees, and their elbows traveling back and fourth in a rocking chair motion. Their biceps are never worked though any real range of motion. Their front delts are doing all the work.

Another error is to curl your wrist up during the move or to hold your wrist in a contracted position throughout the curl. Just like moving your elbows forward, contracting your wrists during a biceps curl also takes tension off the biceps. To combat this, I allow my hands to sag down somewhat while I'm curling. This may bother some people's wrists, but I've never had a problem.

Long-Head Isolator 3: Barbell Drag Curl

For this move, use either a barbell or the Smith machine. You heard me right.

Start by holding the bar with your arms hanging down straight and your little fingers against your outer thighs. Then, drag the bar up along your torso while your elbows move toward the rear. The finish position is when the bar reaches your chest.

Personally, I never felt I got much benefit from this exercise, possibly due to its limited range of motion. Yet others rave about it. Give it a try and form your own opinion.

Short-Head Isolator 1: Preacher Curl

Exercises said to concentrate more on the short head are performed with the elbows in front of the body, normally using a wider grip. The classic example of this is the preacher curl. There's a problem with this exercise: I see people perform it wrong all the time.

Some gym-goers sit at the preacher bench and position the pad against their chest and deep under their armpits. They take a narrow grip and widen their elbows. As the bar comes up they curl their wrists and lean back. The end result is that even if they begin the move with their arms fully straight, the tension quickly comes off the biceps after a few inches of movement.

Why do they perform the exercise this way? It is the path of least resistance. But if that's your goal, why even bother training?

Instead, try this technique for preacher curls: Perform the movement while standing. Raise the pad so it's just below your pecs. Place your lower triceps on top of the pad, so your elbows are just over the edge.

Your elbows should be shoulder width apart and your grip on the bar should flare out slightly, so your hands are a little wider than shoulder width. At the start position, your torso should be leaning backward.

As the bar curls up, lean forward to keep the tension on your biceps. I like to fully supinate my hands so the pressure stays on my little fingers. I let my wrists sag down a bit and I resist the temptation to do a wrist curl as the bar comes up.

Some trainers recommend stopping prior to straightening your arms so you always keep tension on the muscle. However, I'm of the school of thought that you should work a muscle through its full range of motion. You can straighten out your arm while still keeping the tension on the biceps.

Short-Head Isolator 2: Spider Curl

Another great short head exercise is the spider curl. This underutilized movement is also a fantastic way to force yourself to use a full ROM, and because of the way your body is positioned, it's harder to cheat on than some other types of curls.

Use the preacher bench, but turn it around so the 45-degree slope faces you. Raise the pad just enough so that when you lean over it, the bar doesn't hit the supports when your arms are hanging straight down. Then follow the same technique as the preacher curl.

You have to check your ego for this exercise, because you won't be able to handle much weight compared to other movements. It's a good idea to have a partner close by, because once you reach positive failure, the bar refuses to ascend. If you're the type who likes to use a little help to knock out a couple of assisted reps at the end, you'll definitely need that helper here.

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